(a) Biotin, also known as vitamin , is a water-soluble B-vitamin.
It is a coenzyme for carboxylase enzymes, involved in the synthesis of fatty acids, isoleucine, valine and in gluconeogenesis.
Sulphur is a constituent of biotin.
(d) Phosphorus, potassium, sulphur and calcium play an important role in plants growth.
These minerals are required in large amount.
Phosphorus is required for all phosphorylation reactions and constitution of cell membrane, nucleic acids and some proteins.
Potassium is related with protein synthesis, closing and opening of stomata and activation of enzyme.
Calcium regulates metabolic activities, function of cell membrane and stabilizes the structure of chromosomes.
Sulphur is the main constituent of the amino acids, cystine and methionine, coenzymes and vitamins.
(d) Nitrogen, phosphorus, potassium, calcium, sulfur and magnesium are the macronutrients.
The essential elements can be divided into macronutrients and micronutrients.
Nutrients that plants require in larger amounts are called macronutrients.
About half of the essential elements are considered macronutrients: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.
Macronutrients are essential for plant growth and a good overall state of the plant.
The primary macronutrients are Nitrogen (N), Phosphorus , and Potassium (K).
Nitrogen is essential for plant development, since it plays a fundamental role in energy metabolism and protein synthesis.
(d) Plants require potassium ions for protein synthesis and for the opening and closing of stomata, which is regulated by proton pumps to make surrounding guard cells either turgid or flaccid.
(a) Lichens are a symbiotic association between green algae/cyanobacteria and fungi.
(b) Mycorrhiza is a symbiotic association between plant roots and fungi.
(c) Etiolation is caused by light deficiency, not mineral deficiency.
(c) Mg deficiency causes chlorosis (yellowing) due to lack of chlorophyll.
(d) Grey spots of oat (grey speck disease) are caused by manganese deficiency.
(a) N and K are mobile elements; deficiency appears first in older (senescent) leaves.
